1. Field of the Invention
The invention generally relates to a self-propelled harvesting machine.
2. Related Technology
Forage harvesters are harvesting machines that, during harvesting operations, pick up and chop crop material standing or lying in a field and discharge it into a transport vehicle. The transport vehicle drives adjacent to or behind the forage harvester. Although it has already been suggested to saddle mount the transport container on the forage harvester, or to attach a transport trailer to a trailer coupling of the forage harvester, in practice, self-propelled transport vehicles that drive independent of the forage harvester have become common. This makes it possible with fodder material to construct a transport chain from the field to the silo with a plurality of transport vehicles.
When transferring the crop material, the driver of the transport vehicle drives adjacent to or, especially when entering the field, behind the forage harvester. In order to avoid losses from crop material that falls onto the ground instead of reaching the transport container, both vehicles must drive at approximately the same speed. For synchronization, it has been suggested to provide a wireless communication connection with which the movement of the transport vehicle is controlled by the forage harvester or vice versa. Such systems have not in the past become common in practice due to their complexity. Currently, therefore, the driver of the forage harvester equipped with a hydraulic propulsion system specifies a propulsion speed that the driver of the transport vehicle is to maintain.
The speed, in revolutions per minute (RPM), of the internal combustion engine of the forage harvester, is generally constant during harvesting operations, but can be varied by the operator within certain limits. Fuel consumption is unnecessarily high when the internal combustion engine is operated at higher RPM but is only slightly loaded with low throughputs. On the other hand, at lower RPM there is the risk that the internal combustion engine will stall or that the crop material will back up in the discharge channel when higher through-puts are processed.
It has also been suggested to specify the RPM of the internal combustion engine as a function of the width of the crop material attachment and the length of the discharge chute of the forage harvester in order to reduce fuel consumption when the forage harvester has less of a load. Although the RPM of the combustion engine is matched to the throughput, this matching is relatively imprecise and is only a function of the expected through-put, not the actual through-put.
Furthermore, it has been suggested to set the propulsion speed of the forage harvester as a function of the through-put. The RPM of the internal combustion engine remains constant. Although this means the internal combustion engine of the forage harvester can be loaded optimally, the propulsion speed will change at varying densities, which will make it difficult or impossible for the driver of the transport vehicle to drive in synch adjacent to the forage harvester.
In combine harvesters, the RPM of the internal combustion engine is also generally constant during harvesting operations. The thresher and separating devices are driven via gears with a variable transmission ratio, such as with variator drives or planetary gears in which one element is driven by the internal combustion engine and one element is driven hydraulically for RPM variation and one acts as output drive. It has also been suggested to adjust the RPM of the internal combustion engine in order to attain the desired RPM of the threshing and separating rotor. In this case, as well, the RPM of the internal combustion engine depends on the crop material through-put and fuel consumption is therefore not always optimal.
In combine harvesters, the propulsion speed in the prior art is also either specified by the operator or automatically regulated using the through-put. In such an arrangement, in order to facilitate the transfer of the harvested grain from the grain tank of the combine harvester to a transport vehicle, with an activated unloading conveyor it is known to perform the changes in the propulsion speed with a smaller amplification factor. Although this means that the speed does not vary as greatly, it is not constant. In addition, the load on the combine harvester is then not necessarily optimum.
In combine harvesters it has also bee suggested to detect the torque that the internal combustion engine outputs to the driven elements. If the measured torque is lower than a certain threshold value, which indicates that for lower through-puts, for instance in harvesting special crops or non-rectangular blocks, less power is taken off than the internal combustion engine can output at its RPM, the RPM of the internal combustion engine is reduced. A gear transmission between the internal combustion engine and the driven elements, such as the threshing drum, keeps the RPM of the driven elements constant despite the change in RPM in the internal combustion engine. This measurement is relatively imprecise, since it is based on only a portion of the through-put, while the power taken off from the propulsion system is included in the measurement value.